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Mylar balloon = parachute?

Hi all, It seems trivial, but I'm looking for any tips on completing some mylar chutes made from those round balloons you see everywhere. I'm not talking contest-grade here, just something usable for, say, a Big Bertha.

See, I found these great red, white, and blue balloons at the local dollar store before July 4th. Having little cash in my pockets, I thought I'd come back later and get a couple. Naturally, two days later they were gone.

Jump ahead about two weeks, and the clothing store next to the dollar store has a tent sale. Guess what's decorating the tent? (Not to mention the yellow smiley-face balloons -- tempting.)

As luck would have it, my teenage daughter works there part time. I told her to rescue any balloons from the trash, if possible. The last day of the sale, she came home with two badly deflated balloons.

So, at a cost of $0 so far, I'm making parachutes out of them. (Even better than the $2 I was going to spend.)

I haven't made chutes from scratch before, so any tips will be appreciated. Dental floss for shroud lines? Or is there a better idea?

Six shroud lines or eight? (Easier to locate attachment points for eight, I'm thinking.) Length of shroud lines -- 1.5 times the diameter is the rule of thumb, right?

The balloon is round - should I trim it to a hexagon or octagon? The edges want to curl up on the one I cut apart so far. Maybe I should trim the edges somehow to stiffen them?

I'm thinking the red, white, and blue side will be the "inside" of the chute, and thus visible from the ground, while the silver inside of the balloon will be the "outside" of the chute.

Nothing earth-shattering, I know, but it is rocket related, and we can use some lighter topics, right?

-Randy

Reply to
Randy Griffin
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Estes uses heavy guage thread...carpet thread. Any crafts/sewing type store, a buck or two for a big roll. Go to sewing supplies and the big rack with all the thread will have this thicker stuff. The dental floss, which I used before finding this stuff (suggested here by someone on rmr...i can't take credit!) was always too "twisty".

I use one time diameter...actually six sided chutes w/ three strings cut a little more than two diameters. I use six sided with a pattern that I made by taping an estes chute on a piec of cardboard and tracing it, then cutting it. I've made dozens of parachutes with these patterns (one 12", one 18")

Isn't the balloon too rigid? Will it open easily?

Enjoy and let us know how you do!

Art T South Jersey Area Rocketry Society NAR# 34201 L1

Reply to
SirWmOsler

Thanks for the reply, Art. I'll check out the carpet thread. I pass by a Hobby Lobby on my way home from work, so that should be an easy solution.

If I wasn't clear, I cut around the balloon at the seam, leaving two mylar circles about 16" (40cm) in diameter. The mylar is thin enough I think a chute made from it should open OK. Especially in large diameter, eg. Big Bertha type, rockets where it won't be packed too tightly.

I suppose I can overlay an 18" Estes chute and get the attachment points for six lines. I was thinking in terms of folding in half, in half again, then in half again to get eight points.

And I was thinking duct tape for reinforcing the attachment points. Overkill?

Thanks again,

-Randy

SirWmOsler wrote:

Reply to
Randy Griffin

I'd encourage you to run the shroud lines "over the top" like eggloffter chutes, minimizing the likelyhood of tearing the mylar if done the traditional way. I dug up some never inflated mylar balloons from the attic today that I'd thought about trying the same thing with, but had put on the back burner. -- Richard "will also hunt for the elusive carpet thread" Hickok

Reply to
Rhhickok

I use space blanket mylar (picked up 5 blankets on sale for $2.00 each). Mylar WILL set up if left packed or folded. Don't do like I did and prep the rocket at home, then drive to the site. Pack right before launch.

Mylar is strong, but tears easily (oxymoron?). I tape both sides of the attachment point (with packaging tape) and instead of poking through, I use a hot paperclip wire to melt a hole through the tape and mylar. It gives a "sress relieved" hole that doesn't encourage tearing. A non-slip loop knot (bowline) attaches the shroud lines.

Speaking of balloons, anyone tried to inflate a mylar balloon with an ejection charge? Maybe from a baffled ejection system? "Next up on pad

7, a hot air balloon recovery duration model..." :)
Reply to
Gary

we have good results using 3-ring-binder paper reinforcement stickers, the little round jobbies... found a roll of 'em in the garage. skip the duct tape, use package tape instead.

Cliff

Reply to
Cliff Sojourner

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Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

Randy,

The mylar does make good balloons, but it is a bit thick and stiff, good for large BT like you said, but you will need to make sure it's folded, not spiked.

Don't use the duct tape! the glue oozes around the edges and sticks to everything. Clear packing tape, Scotch "Miracle Tape" (thick packing tape) also works well, so do any old floppy disk write protect tabs that still have glue left on them. The best is the thin mylar tape sold by ASP, but it is overkill for non contest chutes.

The next time your daughter goes to work, have her bring home any empty ribbon spools. They make great spool rockets for C-F engines, all they need is two centering rings, a motor tube and a token recovery device.

Bob Ellis

Reply to
bobnrobn

I used a balloon for a parachute. I have been making 8 side parachute. They are easy to do.

1st cut a square the size of the chute you want.

2nd fold it in half then in half again you should have a smaller square

3rd fold it in half to make a triangle then fold that triangle in half again. Know you ahve a line that is shoeter then the other part.

4th cut along the straight line that was mad by folding and there you haveit a 8 side chute.

I use clear paper reinforcements on both side then I tye kevlar for the lines

Any more questions e-mail and I can send some pictures as I make one. snipped-for-privacy@rap.midco.net

Reply to
rocket trike

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